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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.http;
17  
18  import static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
19  import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
20  import static io.netty.handler.codec.http.HttpHeaderValues.X_DEFLATE;
21  import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
22  import io.netty.channel.embedded.EmbeddedChannel;
23  import io.netty.handler.codec.compression.ZlibCodecFactory;
24  import io.netty.handler.codec.compression.ZlibWrapper;
25  
26  /**
27   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
28   * {@code gzip} or {@code deflate} encoding.  For more information on how this
29   * handler modifies the message, please refer to {@link HttpContentDecoder}.
30   */
31  public class HttpContentDecompressor extends HttpContentDecoder {
32      private final boolean strict;
33  
34      /**
35       * Create a new {@link HttpContentDecompressor} in non-strict mode.
36       */
37      public HttpContentDecompressor() {
38          this(false);
39      }
40  
41      /**
42       * Create a new {@link HttpContentDecompressor}.
43       *
44       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
45       *                  more lenient fashion.
46       */
47      public HttpContentDecompressor(boolean strict) {
48          this.strict = strict;
49      }
50  
51      @Override
52      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
53          if (GZIP.equalsIgnoreCase(contentEncoding) ||
54              X_GZIP.equalsIgnoreCase(contentEncoding)) {
55              return new EmbeddedChannel(ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
56          }
57          if (DEFLATE.equalsIgnoreCase(contentEncoding) ||
58              X_DEFLATE.equalsIgnoreCase(contentEncoding)) {
59              final ZlibWrapper wrapper = strict ? ZlibWrapper.ZLIB : ZlibWrapper.ZLIB_OR_NONE;
60              // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
61              return new EmbeddedChannel(ZlibCodecFactory.newZlibDecoder(wrapper));
62          }
63  
64          // 'identity' or unsupported
65          return null;
66      }
67  }